HiI'm currently moving and my new workshop is an extended garage, approx 3mx15m, with a door directly into the house. The outside walls are concrete blocks and there is no ceiling as such although it does have a loft space and pitched roof. I want to improve the insulation to help with condensation issues and improve my comfort levels a bit.

My current scheme is to fix 50mm battens to the walls and attach plasterboard to the battens, insulation the gap behind with polystyrene or whatever is cheap and works best. The ceilings I will probably get someone else to do, basically nailing up plasterboard and fitting 200mm insulation on top.

I would appreciate any suggestion/ideas as this is far from my area of expertise.

We take possession of the house today and I will post pictures later.

Best Regards

picclock

Edit: Since posting this I have had the thought it might be better to use OSB board on the battens rather that plasterboard as this will make it strong enough to screw shelves/fittings directly into the board.

« Last Edit: April 21, 2017, 05:02:38 AM by picclock »

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

OSB is certainly far better than plasterboard for screwing things up (if you see what I mean)...

Shop around for the cheapest panels - best I found was a squeak over £9/sheet provided I bought 10-off at a time. Size wise they're the full 8x4' (2440x1220mm) unlike Wickes plasterboard which is 2400x1200... mix & matching them is slightly awkward to say the least.

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Cheers!Ade.--Location: Wallasey, Merseyside. A long way from anywhere.Or: Zhengzhou, China. An even longer way from anywhere...Skype: adev73

Which thickness of board did you use ?. I was thinking going for 18mm as that way the battens will be spaced at 1200mm and the centre of the board will not be too tender. Best offer I have found is http://www.builderdepot.co.uk/pound-11-70-per-sheet-36no-18mm-x-1220mm-x-2440mm-osb-3-board.html with 36 sheets for £529.20 inc Vat and Del. , which I think is OK as I will have a couple of spares over at the end. Being 1220 wide spacing I can use 1200 mm wide insulation and still have enough space for the battens, 50mm square I thought. Did you use insulation behind and if so what type?

I used the thinnest stuff I could get my hands on, which was (I think) 11mm. I used 600mm stud spacings. I did put noggins between them all, but had to knock most of them out as I managed to set them at the exact height I needed my electrical sockets... (oops).

The 11mm thick wall with 600mm stud (2x3 planed) is plenty strong enough, and my walls are all free-standing, not attached to existing walls like yours will be.

I haven't used any insulation on the outsides (too difficult to get to), I will use rockwool on the roof & the one wall I do have good access to.

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Cheers!Ade.--Location: Wallasey, Merseyside. A long way from anywhere.Or: Zhengzhou, China. An even longer way from anywhere...Skype: adev73

I used the thinnest stuff I could get my hands on, which was (I think) 11mm. I used 600mm stud spacings. I did put noggins between them all, but had to knock most of them out as I managed to set them at the exact height I needed my electrical sockets... (oops).

The 11mm thick wall with 600mm stud (2x3 planed) is plenty strong enough, and my walls are all free-standing, not attached to existing walls like yours will be.

I haven't used any insulation on the outsides (too difficult to get to), I will use rockwool on the roof & the one wall I do have good access to.

I have used the same; 11mm OSB on same spaced studding with noggins at equidistant spacing. As said OSB is much better as I have various shelves & a MMart (usual disc' r ) wall cabinet screwed to mine & they are held up solidly. I have put 1" Celotex insulation foil covered both sides in between the studding with a 1" air gap behind that, proved to be very stable temperature wise in winter & summer. The roof space was plaster boarded then covered with propriety loft 'space blanket'. when the temp outside has been -3* the inside temp has been stable at 7-8*, so above the dew point, helping to prevent rust... I do have a couple of small oil rads to bring the temp up when needed... all nice & cosy.

I've mentioned this before, I used fridge truck (-18°C) insulated panels that I got free from an industrial body builder specialised in Freezer trucks! When an insulated truck tries to get under a bridge that is too low, it wrecks the front, but they have to replace whole panels, leaving a lot of reusable material. The walls are 50mm and the roofs are 80mm. It cost them to have the stuff destroyed! Unfortunately, I don't have any UK contacts for this, but, for large surfaces, (like tractor sheds Andrew!!) it could really be worth while! The attached photo is the North wall of my workshop, with double doors 4m high X 2x2m wide with a "pophole" 2.2m x1m which is my front door! The strap anchors are still in place as the are a real pain to remove. The lower part of the Truck sides are cover with stainless sheet, an added bonus!

@ mechman48You said 1" insulation and a 1" gap. Is it necessary to have a gap? or does it provide some other advantage?. Would it be better to have no gap and just use 1" thick studs?

I don't understand why the wall insulation is so expensive. It appears that the insulation could cost more than the osb. Loft insulation is cheap as chips and presumably(?) would be equally suitable once fitted in place- or maybe not. I have no clue about this stuff

Many thanks for the info.

Best Regards

picclock

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

I used 18 mm OSB3 (the 3 denoting survives in moisture!) for lining the walls of my barn - had to do something as they were sprayed with expanding foam 75mm deep. The 18 mm OSB means I can fix shelves and cupboards, wiring, plumbing etc wherever I want which is really handy. I sprayed it all with white emulsion to get the light levels up a bit.

I assume the gap is to provide a form of moisture barrier; the builder who did mine explained that instead of a vapour barrier (polythene sheeting) next to the wall the gap has the same effect...Plus the foil on the inside of the Celotex... so he says... I s'pose you could use loft insulation in between your studding, the space blanket expands from 3/4" (shrink wrapped) to 4" expanded, & being enclosed in polythene will have same effect...

George.

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George.

Always look on the bright side of life, & remember.. KISS..' Keep It Simple Stupid'

Just on with My workshop at the moment, I am using 25 x 50 treated battens (roofing lath) at 600mm centres with 50mm polystyrene, followed by a visqueen DPM and 3.5mm plywood, which will get a couple or thre coats of washable emulsion The lining is thin, but any shelving can be fixed to the battens!

When I did mine I used loft insulation. The government were forcing the heating companies to help insulate people's houses and for £3 a huge triple roll of 6" thick stuff, they would deliver it and let you fit it yourself, minimum order was about 8 rolls.... The Insulation was secured to make sure it did not sag and spaced off with 2 by 4s, so 6" of insulation is in a 2" gap.

On the inside I have use the thick flooring grade (= waterproof) chip board. Slides nicely together with out any gaps and also works for ceilings and has the advantage you can stand on it if you must

And for some reason I ordered enough extra insulation so that I could do double layers of insulation above the workshop as well

The only failure in the design is the builder who put the garage up for me did not insulate under the concrete flooring, He thought the tools would bee too heavy .

I put 100 mm of expanded polystyrene under mine, with 150 mm of reinforced concrete on top. Actual floor surface is 18 mm OSB3 screwed into the concrete and painted with floor paint. It's had some heavy loads on it

Hi,In recent times there has been a huge increase in the performance of building insulationHigh density foil covered slabs are about 4 times "better" than aerobord or glass fibre loft insulationI would do some research before deciding what to doThe Kingspan website shows a multitude of products, http://www.kingspaninsulation.co.uk/You need to give consideration the actual construction of the concrete wall, is it solid, cavity block or cavity wall constructionCavity walls can be "pumped" with insulation, its also likely that you can claim a home energy grant to improve the standard of the entire house /garage ???

Maybe think what might happen in a fire situation. Personally I'd try to sty clear of Polystyrene. Other materials better in terms of fumes/smoke evolution and resistance to fire spread.

David, I agree entirely that polystyrene is nasty stuff in a fire - not only toxic flumes, but it drips burning globules that cling to clothing. I did however choose to use it under my workshop floor - great 100 mm thick slabs of the stuff - but as it's covered in 6" of concrete I don't envisage many problems, even in a very intense fire

There is an easy solution to the fire problem, try not to set fire to your workshop , and have plenty of extingishers and hosepipes to hand whenever you are doing anything iffy! Kingspan is good, but not fireproof, though it is under normal circumstances, self extinguishing, but not 4 times as good as polystyrene, and VERY expensive. The purpose of all insulation is to trap a layer of air to prevent heat escaping by conduction and convection. Kingspan gets a lot of its "extra" rating from having the reflective foil on it, which only prevents radiated heat escaping, and most buildings have very little true radiated heat in them. Believe me, by the time the fire gets to the polystyrene, I will be long gone and in the next county! The polystyrene in my forge and welding area will be behind plasterboard and skim, which is rated as 30 min fire delay. I have however taken the precaution of removing all the wiring from the insulated roof space. There are many hundreds of thousands of buildings insulated with polystyrene, and the incidence of fires has never been lower, except of course unless you happen to own a recycling yard full of materials you can't sell. Chi-CHING!

@vintageandclassicrepairsThe exterior walls are solid concrete blocks - no cavities. My current thinking is 12mm osb with 30 or 40mm celotex on 50mm battens which will leave a small air gap behind, supposedly for a vapor barrier - which I don't understand.

Not sure what to do about the floor which is a concrete slab. Because the building has been extended the slab has been cast in two parts. Looking at the planning permission info this was done in around 1986, so I,m not sure if planning regs. stipulated foam under the concrete back then for insulation. On the plus side there appears to be no damp at all so it likely works however it was done. Initial thoughts are to just paint the floor with garage floor paint then cover with lino - as I currently have. Any other ideas most welcome.

Best Regards

picclock

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Initial thoughts are to just paint the floor with garage floor paint then cover with lino - as I currently have. Any other ideas most welcome.

How much headroom have you got? If "plenty", and also your bank account is looking fairly robust, you could install under-floor heating... and a false floor. Set the thermostat to 20 degrees (or is it 25 degrees that everything's calibrated to?) and "being cold" will never be a reason to not be in the workshop....

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Cheers!Ade.--Location: Wallasey, Merseyside. A long way from anywhere.Or: Zhengzhou, China. An even longer way from anywhere...Skype: adev73

Hi Picklock, is the exterior of the blocks rendered, and is there any damp patches on the inside of the walls? Check all your gutters and downspouts are clear and not leaking and also the drains they empty in to., and you should be good to go. If the walls are dry on the inside, your spec sounds fine to me. If there is visible damp on the inside, and it is not coming from faulty gutters etc, then use pressure treated timber lath, celotex insulation, then tack building polythene (visqueen( onto the laths, and fit the boards. The floor is unlikely to be insulated under the slab, but will (or at least should have) a dpm under it, and if the floor is totally dry, sounds like there is. Dampness is more often a product of poor ventilation and leaking gutters and roofs than anything else.

Hi picclock,To the best of my knowledge a vapour barrier or breathable membrane should be placed against the concrete wallthis will block any damp coming in but let any moisture outModern membrane is a great improvement over just plastic that can trap moistureYou can fix the timbers through it, lap it out at the floor Make the timbers a tight fit so you can wedge the insulation between themIt depends on what weights etc are going to go on the floor as to what might be best?If no serious weights then a similar battens, insulation and wood will keep the cold at bay

I built a new building with a steel frame and Kingspan insulated cladding a few years ago It is extremely comfortable and very easily heated if needed

@ hermeticHi. The outside walls are rendered but in a slightly odd way. The cement coating is about an inch thick with a ripple pattern, which is overpainted white. There is no apparent dampness in any part of the garage, walls or floor. Although I said it was made of concrete blocks, which most of it is, there are two areas which are made of insulating lightweight blocks. Similar to breeze blocks but with a flat surface finish. Still all dry though.

@ vintageandclassicrepairsI'm not sure how the membrane allows the damp to go one way and not the other. From what I have seen they just appear to be plastic sheets - pretty impermeable in either direction. Am not sure whether to use one or not, though I guess it wouldn't hurt.

@ AdevI don't think my bank balance could run to that, though it sounds like a nice idea. While I was at it could get a carpet fitted with TV, bar and beer fridge - such is the stuff dreams are made of

My other half has put the kibosh on me doing the work and insists on me employing builders as she seems to think it will be too much for me and take too long. I will still get the materials though and and insist it is done to a decent standard. On the other hand I have loads to do without this added ..

Thanks for all the helpful advice

Best Regards

picclock

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

It's important to think in terms of warmth and cold creating condensation in insulated spaces. Whatever side is warmer and contains some humidity will tend to deposit moisture on the colder face. The difference in temperature can be very slight and it still happens. A vapor barrier is a means of keeping warmer moister air from reaching a cold surface to form condensation.

In a heated basement, a moisture barrier, placed in the right location in the whole sandwich is pretty important if you are going to insulate.

A moisture barrier isn't the same thing as a permeable membrane. They don't do the same thing.

Personally, I'd want the moisture barrier against the concrete wall first to isolate the insulation from the cold face and and prevent condensation.

Styrene foam comes in two forms, the beaded type (usually white) and the extruded type (usually pink or blue in the US). The beaded type is formed by steaming hard beads of polystyrene, and it is quite capable of absorbing moisture over the long term. I have some water logged samples of insulating failures here. If water (or more properly, moisture) is kept away from it, it's a good insulation. And even coffee cups are made of it for short term exposure to hot liquids. Nevertheless with long term exposure to moisture it can become waterlogged and lose a lot of its insulative value. It is, for example, not good to place underground against an exterior wall.

Extruded polystyrene is much more resistant to moisture, and would be my foam of choice in a basement interior.

If it is attached to the house building regs will most likely require an inner lining of plasterboard over the OSB for fire retarding. The outside wall needs a vapour barrier on the inside of the insulation behind the plasterboard. If you want a gap between the insulation and the wall blocks it will probably be pointless unless it is vented to the outside otherwise moisture will just move between the wall and the vapour barrier between night and day as the temperature profile shifts. For a spacer use 'corex' the plastic equivalent of corrugated cardboard cut into squares or strips and tacked to the wall. The holes though it allow air circulationThe wall against the house may not need insulation unless it is a cavity wall which will act like a heat chimney up to the roofline. If it is not a cavity wall it should not have a vapour barrier because moisture will be trying to escape from the house more than from the workshop.EPS is up to 20% better than good fibreglass insulation. An 11 in cavity wall is equivalent to 1in of EPS.

Yes, and coming soon to a street near you some political signs. Another possible source if you can find it is they sometimes use it for wrapping large cable drums eg for phone or tv cable though you have to flatten it out again on a hot day.

We have now moved in but I'm nowhere doing the walls/ceiling because I am stuck on the floor !!

On closer inspection of the floor, which is 3 poured slabs done at separate times is not level ( I should say is of many multiple levels) and of poor finish. I would like to get professional help to re-screed and re-level the floor with something like setcrete. I don't think its diy because its over 16 Metres long and to get such a large area (48.6 square metres) level with one pour is quite frankly tricky. I suspect a laser level would have to be used and several people mixing and tamping to get it decent.

Does anyone know the trade name that this would come under ?. Floor fitters are mainly carpenters, plasterers don't do floors etc. Its not easy finding someone without having a job name

Best Regards

picclock

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Thanks for the feedback and further assistance.I finally got someone whose been doing it for 13 Years. I tend to use checkertrade or mybuilder.com as they have customer feedback, and can supply local artisans. Problem was despite contacting three lots on checkertade with two no replies and one request to visit and assess who didn't turn up, and then trying on mybuilder with no results I was getting a bit desperate, but mybuilder came through. The chap does car showrooms and similar and has some good pictures on Facebook. After a visit he reckons it will take about 30 bags of latex self levelling compound. He is round Friday to seal it and fill in the deep areas, then him and a mate will do it Saturday morning.

Will try and post before and after pictures. Its a very deceptive floor in that its only when you put a straightedge and level on it you can see how bad it is. There are very few places where my ladder will sit with all four feet touching.

Best Regards

picclockBest Regards

picclock

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Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

The floor is latexed , but the finish is not as good as it should be. The chap doing had cut his knee with a hooked stanley blade and it was stitched up by hospital, which along with the painkillers may have contributed to the issues. However, its adequate and miles better than the crumbly concrete that was there before.

I have just started putting up the battens and insulation which is going well on the whole. Although I have fitted one OSB sheet its too heavy for me to handle on my own so I am getting some help in for that. For the ceiling I have decided to go with a suspended one with insulation on top. Have done quite a few tests on LED bulbs and the two winners are Integral 12.5W for 1521 Lumens and the philips corepro 13.5W @1521 Lumens. They are both about £5 or less depending on quantity, but the Integral lamp has, to my eyes a higher CRI, and uses 8% less power. The supposedly high output junk on ebay is a shadow of the winners. Used a light meter to measure.

I do have a problem with fitting the cut down sheets of polystyrene. The full size sheets work OK but when it comes to the ends of the wall next to the piers they are never square or straight, often waisted in the centre. Its no problem cutting to the shape, but transferring the required size to the sheets is proving very difficult. I am getting by by hand cutting in the last few mm with a stanly knife, but I am sure there must be a better way. Any thoughts or ideas in this area much appreciated.